title: Scatter correction for large non-human primate brain imaging using microPET.
abstract: The baboon is well suited to pre-clinical evaluation of novel radioligands for positron emission tomography (PET). We have previously demonstrated the feasibility of using a high resolution animal PET scanner for this application in the baboon brain. However, the non-homogenous distribution of tissue density within the head may give rise to photon scattering effects that reduce contrast and compromise quantitative accuracy. In this study, we investigated the magnitude and distribution of scatter contributing to the final reconstructed image and its variability throughout the baboon brain using phantoms and Monte Carlo simulated data. The scatter fraction is measured up to 36% at the centre of the brain for a wide energy window (350-650 keV) and 19% for a narrow (450-650 keV) window. We observed less than 3% variation in the scatter fraction throughout the brain and found that scattered events arising from radioactivity outside the field of view contribute less than 1% of measured coincidences. In a contrast phantom, scatter and attenuation correction improved contrast recovery compared with attenuation correction on its own and reduced bias to less than 10% at the expense of the reduced signal-to-noise ratio. We conclude that scatter correction is a necessary step for ensuring high quality measurements of the radiotracer distribution in the baboon brain with a microPET scanner, while it is not necessary to model out of field of view scatter or a spatially variant scatter function.
authors.affiliation: Discipline of Medical Radiation Sciences, Faculty of Health Sciences, University of Sydney, PO Box 170, Lidcombe, NSW 1825, Sydney, Australia. snai3212@uni.sydney.edu.au
authors.forename: S
authors.initials: S
authors.lastname: Naidoo-Variawa
authors.forename: W
authors.initials: W
authors.lastname: Lehnert
authors.forename: R B
authors.initials: RB
authors.lastname: Banati
authors.forename: S R
authors.initials: SR
authors.lastname: Meikle
mesh_terms: D000818:Animals; D016477:Artifacts; D001921:Brain / Q000000981:diagnostic imaging*; D005260:Female; D007091:Image Processing, Computer-Assisted / Q000379:methods*; D010215:Papio; D019047:Phantoms, Imaging; D049268:Positron-Emission Tomography / Q000379:methods*; D015203:Reproducibility of Results; D012542:Scattering, Radiation